Have Your Say: What's Your Favorite Whodunnit?

While North America will have to wait until Friday, Kenneth Branagh's adaptation of Agatha Christie's Murder on the Orient Express is currently already in cinemas across the United Kingdom and Ireland. It's not exactly the first time someone tackled this particular story; in my lifetime there have been four previous ones that I'm aware of, and one of those was a four-and-a-half hour Japanese television series, released only two years ago!

It's easy to see the appeal of the story though: a bunch of colorful characters get thrown together in a remote location, someone gets murdered, and for the master detective who tries to solve "who did it", everyone turns out to be a suspect with a sordid or hidden past. It's almost tailor-made for actors to shine in.
While thrillers and mysteries are still popular, for a while the "Whodunnit" variety was a powerful and omnipresent genre in itself, and many a classic film belongs in it.

Which brings us to our question of the week: what's your favorite "Whodunnit" film, and why? Chime in, in the comments below, and HAVE YOUR SAY!